RFID tags are known in the art. These so-called tags often assume the form factor of a label or a literal “tag” but are also sometimes integrated with a host article and/or its packaging. RFID tags typically comprise an integrated circuit and one or more antennas. The integrated circuit typically carries out a variety of functions including modulating and demodulating radio frequency signals, data storage, and data processing. Some integrated circuits are active or self-powered (in whole or in part) while others are passive, being completely dependent upon an external power source (such as an RFID tag reader) to support their occasional functionality.
There are proposals to utilize RFID tags to uniquely identify individual items. The Electronic Product Code (EPC) as managed by EPCGlobal, Inc. represents one such effort in these regards. EPC-based RFID tags each have a unique (within the EPC universe) serial number to thereby uniquely identify each tag and, by association, each item associated on a one-for-one basis with such tags. (The corresponding document entitled EPC Radio-Frequency Identity Protocols Class-1 Generation-2 UHF RFID Protocol for Communications at 860 MHz-960 MHz Version 1.0.9 is hereby fully incorporated herein by this reference.)
In some cases a system designer will seek to provide more-or-less ubiquitous coverage through a given facility (such as a retail store) and thereby have the theoretical ability to read an RFID tag regardless of where that tag might be located within the facility. By one approach, for example, a plurality of RFID-tag readers may hang suspended from the ceiling of the monitored facility. Examples in such regards can be found, for example, in U.S. patent application Ser. No. 12/900,191, entitled METHOD AND APPARATUS PERTAINING TO RFID TAG READER ANTENNA ARRAY, the contents of which are also fully incorporated herein by this reference.
Unfortunately, while it can be very helpful to read a particular RFID tag to thereby gain its tag-specific information, to a very large extent the system can remain quite effectively blind to the physical location of that RFID tag within the monitored facility (as the RFID tag itself has no such physical-location information to impart). This lack of useful information regarding physical location becomes even more acute when taking into account the fact that coverage areas for different RFID-tag readers can and will overlap.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.